$(window).ready(function(){
  var r = parseInt(Math.random()*256);
  var g = parseInt(Math.random()*256);
  var b = parseInt(Math.random()*256);
  var a = Math.ceil(Math.random()*10) / 10;
  var map = document.getElementById('map');
  map.style.background = "rgba("+ r +","+ g +","+ b +","+ a +")";
});
